This disclosure relates to device to device communications and more particularly to use of resources in a system enabling wireless device to device communications.
A wireless communication system can be seen as a facility that enables communication sessions between two or more nodes such as fixed or mobile wireless devices, user equipment, machine type terminals, access points such as base stations, and so on. A wireless device is provided with an appropriate signal receiving and transmitting arrangement for enabling communications with other parties. A communication system and compatible devices typically operate in accordance with a given standard or specification which sets out what the various entities are permitted to do and how that should be achieved. For example, the standards, specifications and related protocols can define the manner how and what the devices shall communicate with, how various aspects of the communications shall be implemented and how the devices shall be configured. Examples of wireless systems include public land mobile networks (PLMN) such as cellular networks, satellite based communication systems and different wireless local networks, for example wireless local area networks (WLAN). Examples of wireless systems are those based on standards by the 3rd Generation Partnership Project (3GPP). Recent 3GPP developments are referred to as the long-term evolution (LTE) and the LTE-Advanced (LTE-A) of the Universal Mobile Telecommunications System (UMTS) radio-access technology.
A type of communication services is known as the Device-to-device (D2D) communications where two or more devices can directly communicate with each other. Examples of D2D communications include direct communications in a cluster of proximity devices, integrated network-controlled D2D communications and autonomous D2D communications in cellular network, grid/group of local machines communicating with each other while performing certain tasks in co-operative way, ad-hoc networks and advanced cellular devices acting as a gateway for a number of low-capability devices or machines to access cellular network. Examples of alternative terms for such communications include mobile-to-mobile (M2M), machine-to-machine (M2M), terminal-to-terminal (T2T) or peer-to-peer (P2P) communications.
D2D communications can be network controlled. In network controlled D2D solutions the individual devices may have cellular and/or D2D radio bearers configured. The cellular bearers can comprise at least some default signalling bearers. In certain circumstances a D2D mode and D2D radio bearer (RB) services are believed to provide a better performance in terms of e.g. resource utilization, network performance and/or end-user experienced quality of service (QoS) than what might be achieved by using a regular cellular access mode and radio bearer services thereof. Depending on user cases, user traffic may remain local between the devices e.g. in direct D2D for end-to-end (E2E) applications or be routed through a serving access network to devices connected to wider communication system, for example in relay or mobile gateway applications. Furthermore, D2D communications may be provided as an in-band service which shares the same radio resource as regular cellular transmissions, or as an off-loaded out-band service which does not interfere with the regular cellular transmissions.
In accordance with a prior art proposal a reference bearer service model can be used for network controlled D2D communications with help of a multi-operator coordinating-and-controlling central server. Another proposal is that a network can configure QoS parameters for a D2D radio bearer with allowable variations so that D2D devices can then adjust their D2D protocol operation modes by themselves including radio link control (RLC) mode selection, hybrid automatic repeat request (HARQ) settings and power control.
The inventors, however, have found that these may not work satisfactorily in all circumstances. For example, it might be desirable for QoS provisioning and control functions for D2D radio bearer services to be able to ensure fast switching between a D2D mode and a regular cellular access mode. Also, in certain applications flexible resource allocation and/or adaptation to D2D radio transmissions as well as use cases or applications might be desired. Overhead for a cellular network controlling the D2D services should also be kept on reasonable levels.
It is noted that the above discussed issues are not limited to any particular communication environment and station apparatus but may occur in any appropriate system where network assisted device to device communications may be provided.